Valve for the addition of water to electrochemical accumulator batteries

ABSTRACT

A valve for the addition of water to electrochemical accumulator batteries and for maintaining the flow of liquid at a constant level. A membrane in a valve body is biased by means of a spring against a wall arranged concentrically with an inlet orifice, the wall creating an inner chamber of circular cross-section, and an outer chamber which is of annular cross-section and is connected to an outlet connection via a constricted orifice. A spindle at the center of the membrane passes freely through the inlet orifice and exhibits outside the latter a conically enlarged part, the cross-sectional area of which increases in proportion to the distance to the inlet orifice, serving as a valve seat, and which is intended to provide a seal when the spring yields to the membrane.

TECHNICAL FIELD

The present invention relates to a valve for the addition of water toelectrochemical accumulator batteries comprising a valve body providedwith an inlet connection to the valve body and an outlet connection. Avalve of this kind is intended to constitute part of an arrangementcomprising level-controlling devices for each cell in a battery for thesupply of water to the cell up to a predetermined maximum level, saiddevices being connected to a line for the supply of water and for theventilation of the gas spaces of the cells, wherein one end of the lineis connected to a valve in accordance with the invention for the purposeof controlling the supply of water and the other end of the lineprovides ventilation to the atmosphere via a riser pipe.

TECHNICAL BACKGROUND

A number of different arrangements for the addition of water toelectrochemical accumulator batteries are already known. A commonfeature of these is that each cell has devices which permit the supplyof water to a predetermined maximum level. The function of these devicescan be based on ghe hydrostatic effect or on floats in differentvariants. The devices are attached in series or parallel connection to astorage container for water.

The systems differ primarily with regard to the arrangement of thesupply of water to the level-controlling devices. This object may appeartrival, although in practice it has proved difficult to resolve withregard to the requirement for flexibility of the design and low cost. Asuitable system should, in fact, be capable of being applied to:

batteries with cells positioned in groups on different planes, such asin a stepped frame, on shelves positioned vertically beneath oneanother, or on an inclined plane, such as a floor which slopes towards afloor drainage channel;

battery installations in a concealed or not easily accessible position,such as in railway wagons and diesel locomotives, etc.;

batteries whose cell enclosures can exhibit considerable differences inrespect of their material, construction and thus even theirsensitiveness to pressure, for which reason the applied positive ornegative pressure should be small, so that the capacity of the containeris not affected to any significant degree or the risk of fracture iseliminated; consequently, any series of level-controlling devicesconnected together via an inlet supply line should be short, havingregard to the unavoidable drop in pressure in the line, since thefilling time would otherwise be unacceptably long;

batteries ranging in size from only a few cells up to several hundredcells; it is necessary in the case of the larger batteries, in view ofthe risk of leakage currents, for these to be divided up into anappropriate number of cell groups, to which the water supply is providedvia separate lines.

Previously disclosed in GB No. 1 142 633 is a filling system which makesuse of a storage container positioned beneath the outlet level of thelevel-controlling devices installed in the cells. The water is conveyedfrom the storage container by means of a pump either directly to thelevel-controlling devices or indirectly to these via a reservoirpositioned at a higher level with a gravity feed to the cells. Anysurplus water is returned by gravity to the storage container positionedat a lower level. The arrangement requires the availability of a mainselectricty supply and is unsuitable for multi-cell batteries, for whicha number of separate water supply branches are necessary.

A similar arrangement is disclosed in GB No. 2 041 629, which differsfrom the arrangement described above essentially in that water from astorage container is sucked into the level-controlling devices by meansof a pump attached to the storage container.

This system suffers from the same disadvantages as the system disclosedin GB No. 1 142 633. Furthermore, negative pressure can be created whichmay damage the cells. By introducing a filling container in seriesbetween the storage container and the cells at a height such that thefluid levels in the filling container and the cells are essentiallyidentical, it is possible to avoid harmful negative pressure, as may beappreciated from SE No. 7910526-8. This arrangement makes use of acentral reserve of battery fluid, from which a pump conveys fluid to theaforementioned filling container on the cells. The fluid is sucked fromhere to the cells by the level-controlling devices, and any surplus isreturned to the storage container. This complicated arrangement issuitable only for the filling of batteries with relatively few cellspositioned on the same plane.

Contrastingly simple is an arrangement described in DE No. 23 03 244, inwhich cells with level-controlling devices are supplied with water bygravity from a storage containerpositioned above the electrolyte levelof the cells. In spite of its simplicity this principle is notapplicable to multi-cell batteries, in which the necessary level vesselswould result in an installation which is difficult to monitor andonerous to maintain.

Previously disclosed systems, such as those mentioned above, may be wellsuited to certain applications, although they lack the necessaryflexibility for them to be able to satisfy the fluctuating demands whichmay be placed on a filling arrangement in accordance with the above listof demands, the purpose of which is to achieve reduced maintenance coststhrough lower servicing requirements and/or rapid servicing of thebattery installations, yet retaining high operational reliability inconjunction with a low cost for the arrangement and the installation.

THE INVENTION

This problem is solved through the present invention by means of a valvefor controlling the supply of water, which is characterized in that amembrane sealingly arranged in the valve body is biased by means of aspring against a wall arranged inside the valve body concentrically withthe inlet orifice, said wall dividing a space created by the membraneand the valve body into an inner chamber of circular cross-sectiontowards the membrane and is connected to the outlet connection via aconstricted orifice, wherein the membrane is provided at its centre witha spindle which passes freely through the inlet opening, in this wayreduced to an annular slot, and which outside the inlet orifice has aconically enlarged part, the cross-section area of which increases inproportion to the distance to the inlet orifice and which is intended toprovide a seal when the spring yields to the membrane.

This valve can, as has already been mentioned, form part of anarrangement for the filling of water into electrochemical accumulatorbatteries containing level-controlling devices which permit the additionof water to each cell in a battery up to a predetermined maximum level,said devices being connected to a line for the supply of water and forthe ventilation of the gas spaces of the cells, wherein one end of theline is attached to a valve in accordance with the invention for thepurpose of controlling the supply of water and the other end of the lineprovides ventilation to the atmosphere via a riser pipe. In anarrangement of this kind the valve should be positioned in closeproximity to a level-controlling device.

A storage container for water can, according to one embodiment, bepositioned at a sufficient height above the valve for its openingpressure to be exceeded by the head of water.

Alternatively a pump, preferably a centrifugal pump, can convey waterfrom a storage container to the valve at a pressure which exceeds theopening pressure of the valve.

The riser pipe preferably discharges into an explosion-suppressingvalve.

The cells can be arranged on one and the same plane or on differentplanes, such as in a stepped frame.

In an embodiment, which is particularly suitable for multi-cellbatteries, the cells can be connected together in series in groups viathe level-controlling devices to a line for the supply of water and forthe ventilation of the cells, wherein each line is connected at one endin close proximity to a valve for regulating the supply of water and atthe other end to a riser pipe.

Each group of cells which is connected to a supply line mayappropriately consist of 1-30 cells. The valves may appropriately beattached in parallel to a storage container for water.

The expression `water` shall also be understood to denote any otherbattery fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now described in greater detail with reference to theaccompanying drawings, in which

FIG. 1 shows an example of a valve according to the invention in crosssection;

FIGS. 2A, B, and C illustrate the mode of operation of the valve inthree different valve positions;

FIGS. 3-6 schematically show different arrangements for the addition ofwater according to the invention;

and FIG. 7 in a vertical section shows a valve according to theinvention connected to a level-controlling device in an electrochemicalcell.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The reference numeral 10 is used in the Figures to denote a valveaccording to the invention for the addition of water to electrochemicalaccumulator batteries. The valve consists of a valve body 12 of circularcross-section with an inlet connection 14 having a circular orifice 16facing towards the valve body, serving as a valve seat, and with anoutlet connection 18 with a constricted orifice 20 facing towards thevalve body.

A cover 22 secured to the valve body by means of screws 23 sealinglyconnects a membrane 24 to the valve body but has opening 25 to thesurrounding atmosphere. A spring 26 supported against the cover 22biases the membrane 24 against an annular seat defined by a wall 28arranged concentrically with the inlet orifice 16 inside the valve body,said wall dividing the space inside the valve body into an inner chamber30 and an outer chamber 32, the inner exhibiting annular cross-sectiontowards the membrane. At the centre of the membrane is a valve spindle34 passing freely through the inlet orifice 16, which in this way isreduced to an annular slot. Outside the inlet orifice 16 the spindle hasa conical part 36, the cross-sectional area of which increases with thedistance from the valve seat 16 and which is intended to provide notonly a change in the area of the slot, but also a seal when the spring26 yields to the membrane 24. The membrane 24 can appropriately bemoulded from rubber, for example EPDM rubber, as an integral unittogether with the spindle 34 and the conical part 36. The membrane andthe spindle may, however, constitute separate components which arejoined together in an appropriate fashion. Only the annular part of themembrane in the outer chamber 32 needs to be elastic to any significantdegree. The spring 26 can appropriately consist of stainless springsteel, whilst the valve body 12 and the cover 22 may appropriately beinjection moulded in a plastics material such as propylene.

The valve has three different functions, which are achieved with onlyone signle moving part. The valve has a distinct opening pressure, thatis to say the fluid pressure in the inlet pipe must exceed apredetermined value before the valve will open to permit a flow to passthrough. Once this condition has been met, fluid will flow through thevalve, which will then maintain the rate of flow at a constant level.The third function takes effect when a counter-pressure occurs in theoutlet pipe, in which case the flow rate is reduced and the valve closesfully at a certain counter-pressure.

These functions are vital if controlled conditions are to be providedfor the addition of water to electrochemical accumulators; it is herebyimportant:

that the flow of water to the cells is adjusted in such a way that itwill permit a certain promptness and continuity during the fillingoperation, but that it will not exceed a certain, predeterminedthreshold value above which the simultaneous ventilation of the gasspace in the cells is rendered difficult or is prevented;

that the pressure of the water supply to the cells remains unaffected bythe water pressure acting against the valve and is adjusted in such away that harmful over-pressure cannot arise in the cells;

that the valve has a minimum opening pressure for the flow to the cells,mainly in order to prevent the passage of gas from the cells via thevalve; and

that the flow through the valve ceases at a certain counterpressure.

The functions of the valve are illustrated as positions A, B and C inFIG. 2, from which the reference designations have been omitted for thesake of clarity. In FIG. 2 A the membrane 24 is resting against the wall28. The inlet via 14 is open towards the inner chamber 30, but theoutlet via the outer chamber 32 and the connection 18 is closed. Thiscondition will continue to exist for as long as the inlet pressure onthe surface of the membrane in the inner chamber 30 is below a minimumvalue balanced by the spring force.

If this value is exceeded, the spring 26 will yield to the membrane 24and will open to the outer valve chamber 32 and thus to the outlet 18.The valve will then be in the FIG. 2B position. The incoming water, thepressure of which has just caused the spring to yield to the membrane,will at the same time also be allowed to enter the outer valve chamber,in which case it will act on the exposed surface of the entire membranefacing towards the chambers. The spring is then operating against aproportionally greater force, which widens the opening between themembrane and the chambers so as to permit a stable flow. In this way thevalve is insured a distinct opening for a flow through same.

The flow through the valve in FIG. 2B is continuous and constant,provided that the counter-pressure on the outlet side is comparativelylow and is also constant. The flow reduces, however, as thecounter-pressure increases and comes to a complete halt at a certainpredetermined value. This condition is represented in FIG. 2C. Thespring in this case has yielded further to the membrane, so that theconical part 36 on the spindle 34 seals against the valve seat 16.

The dimensioning of the spring 26, which regulates the movements of themembrane 24 and also the opening and closing of the inlet orifice,determines the operating pressure of the valve, that is to say theminimum pressure for opening towards the outer valve chamber and thepressure for closing the inlet 16. The desired flow is determined by theappropriate selection of surface areas for the inlet slot between theinlet 16 and the conical part 36 of the spindle and for the outletorifice, i.e. the constriction 20. Adjustable calibration of the spring26 can, of course, be achieved, if this is considered to beadvantageous, by means of an adjustable attachment in the cover 22.

In the case of a continuous flow the membrane will alternativelyincrease and reduce the inlet slot, that is to say it will alternatebetween the positions of FIG. 2B and FIG. 2C, whilst maintaining thepredetermined operating pressure and thus the predetermined flow ratethrough the outlet orifice. The flow through the valve is unaffected byvariations in the pressure on the feed side, provided that it is abovethe minimum pressure for opening the valve.

Generally speaking, this valve provides a constant flow regulation for aliquid.

The various functions of the valve make it particularly well suited foruse as a device for regulating the supply of water to arrangements forthe addition of water to electrochemical accumulator batteries. Examplesof such arrangements are shown in FIGS. 3-6. Each such arrangementcontains level-controlling devices 38, which permit the supply of waterto each cell 40 in a battery 42 up to a predetermined maximum level 44.The levelcontrolling devices 38 are connected to a line 46 for thesupply of water and for the ventilation of the gas spaces of the cells.A valve 10 in accordance with the invention is attached to one end 48 ofthe line 46 in close proximity to a level-controlling device. The otherend 50 of the line 46 is connected to a riser pipe 52 for ventilation tothe atmosphere.

In one embodiment, shown in FIG. 3, the valve 10 is connected via a line56 to a storage container 58 for water positioned at a sufficient heightabove the valve for its opening pressure to be exceeded by the head ofwater. The riser pipe 52 discharges preferably into anexplosion-suppressing valve 54.

The storage container 58 for water can also be positioned low inrelation to the cells, in which case a pump 60--preferably a centrifugalpump--forces water through the line 56 to the valve 10; see FIG. 4. Thecells can be arranged, as desired, either on one and the same plane, asshown in FIGS. 3-5, or on different planes, such as in a stepped frame62, as shown in FIG. 6.

The function of the level-controlling devices 38 can be illustrated withthe help of FIG. 7. This provides a detailed picture of a membrane valve10 in accordance with the invention, which is connected via the end 48of the line in close proximity to a level-controlling device 38 in thefirst of several cells 40 included in a battery 42, for example as shownin FIG. 3.

As mentioned by way of introduction, various types of level-controllingdevices have been disclosed. The choice of any of them is of noconsequence for the function of a water addition arrangement inaccordance with the invention. The device 38 shown in FIG. 7 exhibitshose connections 66 and 68, respectively, for the inlet and the outletof the water flow, which is led to the cell 40 from a storage container58 (not shown here) through the line 56 and via the valve 10, the line48 and the connection 66, and is then conveyed to the next cell throughthe connection 68 and the line 46.

The level-controlling device 38 has a lower and an upper water trap 70and 72 respectively. The water flow in the device 38 follows the pathindicated by a thick arrow, via a column 74 to the electrolyte space ofthe cell, at the same time as air battery gases are evacuated via achannel 76 along the path indicated by a thin arrow. The water flow tothe cell ceases when the electrolyte level has risen to the indicatedmaximum level 44, in which case the lower opening of the column 74 hasbeen closed off by the electrolyte of the cell and a pressure equivalentto the pressure level determined by the valve 10 at the water trap 70has been built up inside the column 74.

The water flow from the valve 10 may preferably be so adjusted that onlya few cells, perhaps one quarter to one half of the cells are filledsimultaneously in a series supplied from the same valve. The first cellin the direction of the flow takes a greater proportion of the flow thanthe following cells and is thus filled most quickly, and the immediatelyfollowing cells are filled progressively more slowly. Once the firstcell is full, the immediately following cells will have a greaterproportion of the flow to distribute, and filling continues in this wayuntil the last cell in the series has been filled. The water is thenconveyed further, see FIG. 3, to the riser pipe 52 via the line 50,where it rises to a height corresponding to the counterpressurenecessary for the valve 10 to close off the flow of water.

By regulating the flow in the manner indicated, abundant space isprovided for conducting away air and battery gases from the cells, whichis important if the desired level of filling in the cells is to bereliably achieved. The valve 10 should be connected close to andapproximately on a level with the first level-controlling device 38 in aseries, as may be appreciated from FIG. 7, so that the predeterminedoperating conditions for the valve, which are not subsequentlyadjustable, can be utilized to the full extent. The valve thus ensuresthat the desired flow and pressure conditions are maintained in thefilling arrangement, irrespective of the positioning of the waterstorage container, and it ensures that the battery gases are always ledaway from the installation via the riser pipe, possibly through anexplosion-suppressing valve 54 installed thereon.

The valve 10 also prevents the water line 56 leading from the storagecontainer 58 from being emptied of water at the closure of the valvewhen a container installed in a low position is used; see FIG. 4.Disturbances in the function of the level-controlling devices 38, ofwhich there is a risk if airlocks are formed in the line 56 and areintroduced into the line 46 on opening the valve, can be avoided in thisway.

According to a further embodiment of the invention the cells 40 areconnected in series through level-controlling devices 38 in groups 64with a line 46 for each group, in which case each line 46 is attached atone end 48 in close proximity to a valve 10 for regulating the watersupply and is attached at its other end 50 to a riser pipe 52. Thisembodiment is represented schematically in FIGS. 5 and 6.

This embodiment is applicable in particular in the case of batterieswith a large number of cells in order to ensure the desired rate offilling. Each series should not normally, therefore, consist of morethan about 30 cells. The number is dependent, however, on the size ofthe cells, the desired rate of filling and the relative positioning ofthe cells, etc. Individual cells positioned on planes one beneath theother may thus each require its own valve in order to function reliably.It is acordingly reasonable to set the limit for a group at between 1and about 30 cells.

Each valve 10 is attached to a storage container 58 for water,preferably through parallel connection on a supply line 56.

INDUSTRIAL APPLICATION

The invention offers a highly flexible, yet very cheap system for theaddition of water to electrochemical accumulator batteries applicable toall power sources which call for the addition of water, irrespective ofthe size, the number or the relative positions of the constituent cells,and irrespective of whether or not a mains power supply is available.The system incorporates a controlled gas release facility and anotherwise sealed water system. It is also robust and well suited to bothstationary and traction applications.

I claim:
 1. Apparatus for the addition of water to electrochemical accumulator batteries, said apparatus comprising: a plurality of battery cells; level-controlling means for each cell for regulating the addition of water to the cell up to a predetermined maximum level, said level controlling means connected to a supply line for the supply of water and for ventilation of gas from spaces in the cells; valve means connected with the supply line adjacent one end of the line for controlling the supply of water, said valve means arranged in close proximity with one of said level controlling means, said valve means including a valve body, an inlet connection extending from said valve body and including an inlet orifice communicating with the interior of the valve body, an outlet connection extending from said valve body and communicating with the interior of the valve body, a wall within the valve body positioned substantially concentrically with the inlet orifice, a membrane within the valve body, spring means for biasing said membrane against said wall, said wall dividing a space defined between the membrane and the valve body into an inner chamber of circular cross-section and an outer chamber of annular cross-section, said space communicating with the outlet connection through a constricted orifice, a spindle substantially centrally positioned on the membrane, said spindle passing freely through the inlet orifice to define an annular slot therewith, said spindle including a conically enlarged portion which extends outside the inlet orifice and has a cross-sectional area which increases in proportion to the distance from the inlet orifice and which closes the inlet orifice when fluid pressure acting on the membrane compresses the spring means; and a riser pipe connected to the other end of the water supply line.
 2. Apparatus in accordance with claim 1, including storage container means for water connected with the supply line, said storage container means positioned at a sufficient height above the valve means for providing a head of water sufficient to overcome the force of the spring means and thereby provide an opening pressure for said valve means.
 3. Apparatus in accordance with claim 1, including pump means in communication with the supply line for moving water from a storage container at a pressure that exceeds the force of the spring means and thereby provide an opening pressure for said valve means.
 4. Apparatus in accordance with claim 1, wherein the riser pipe discharges into an explosion-suppressing valve.
 5. Apparatus in accordance with claim 1, wherein the cells are arranged on a single plane.
 6. Apparatus in accordance with claim 1, wherein the cells are arranged on different planes.
 7. Apparatus in accordance with claim 1, wherein the cells are connected in series in groups through the level-controlling means to a supply line for each group of cells for the supply of water and for the ventilation of the cells, and to the valve means for regulating the supply of water, each supply line connected at one end to said valve means and at the other end to a riser pipe.
 8. Apparatus in accordance with claim 7, wherein each group of cells connected to a supply line includes from 1 to about 30 cells.
 9. Apparatus in accordance with claim 7, wherein the valve means includes plural valves that are connected in parallel with storage container means for containing water. 